During my time in Timbuktu, several locals denied that the city was unsafe and beseeched me to "tell the Europeans and Americans to come." But for much of the past decade the U.S. State Department and the foreign services of other Western governments have advised their citizens to avoid Timbuktu as well as the rest of northern Mali. The threats originate from a disparate collection of terrorist cells, rebel groups, and smuggling gangs that have exploited Mali's vast northern desert, a lawless wilderness larger than France and dominated by endless sand and rock, merciless heat and wind.

Most infamous among the groups is the one led by Mokhtar Belmokhtar, an Algerian leader of al Qaeda in the Islamic Maghreb (AQIM). Reputed to have lost an eye fighting the Russians in Afghanistan, he is known throughout the desert by his nom de guerre, Belaouer, Algerian-​French slang for the One-Eye. Since 2003, his men have kidnapped 47 Westerners. Until 2009, AQIM had reached deals to release all of its hostages, but when the United Kingdom refused to meet the group's demands for Edwin Dyer, a British tourist, he was executed—locals say beheaded. His body was never found. In the weeks before my arrival, Belaouer and his cohorts had acquired a new inventory of hostages: three Spanish aid workers, an Italian couple, and the Frenchman.

"Belaouer is very clever," the salt merchant empha­sized. He described how AQIM gained protection from the desert's Arab-speaking clans through Belaouer's marriage to the daughter of a powerful chief. One popular rumor describes him giving fuel and spare tires to a hapless Mali army patrol stranded in the desert. Such accounts have won him sympathizers among Timbuktu's minority Arab community, which in turn has angered the city's dominant ethnic groups, the Tuareg and Songhai.

Up on the roof the temperature had dropped. The salt merchant pulled a blanket around his shoulders and drew deeply on his cigarette. To the north, the city's lights gave way to the utter blackness of the open desert. He told me that the price AQIM had set for the Frenchman's life was freedom for four of its comrades arrested by Malian authorities last year. The deadline to meet these demands was four weeks away.